Throat plate construction



v'are States The present invention relates to the feed stations of circular knitting machines, and has particular application to a novel throat plate construction for such stations.

The conventional metallic throat plate of circular knitting machines is subject to substantial Wear, particularly when knitting with nylon and other synthetic yarn. During the major portion of the normal operation of the knitting machine, the yarn is positioned in and travels over the one corner of the throat plate, with the result that frequently, the yarn Wears a nick or groove into the throat plate at that corner. When the operation of the knitting machine requires oscillation of the cylinder with the consequent necessity for the yarn to travel across the face of the throat plate, the engagement of the yarn in the groove or nick is likely to cause a flaw in the stocking due to the improper tension applied to yarn by the nick in the throat plate. It may be some period before the aw is detected and the cause is determined, with the result that a substantial number of stockings may be defective before the throat plate is replaced.

Attempts to overcome this diilculty by the use of ceramic throat plates or ceramic inserts for throat plates have not been entirely satisfactory because of the difficulty in machining the ceramics to the proper tolerances for the knitting machine, and the extreme brittleness and fragility of the wear-resistant ceramic materials. Suitable ceramic materials used for this `and similar purposes in the textile industry are compositions containing alumina, silica and/ or magnesia, for example Alsimag 614.

With the foregoing in mind, a primary object of the present invention is to provide a novel throat plate construction which utilizes ceramic material in the critical parts thereof, but which protects the ceramic material from impact of the feed fingers, or other instrumentalities of the knitting machine.

More particularly, the present invention provides a throat plate comprising a non-ceramic support portion having a ceramic portion united therewith, the precision surfaces of the ceramic portion being of a form which is readily machined.

The present invention provides a throat ring which is capable of highly economical production, but which is fully effective to serve its intended function.

All of the objects of the invention are more fully set forth hereinafter with reference to the accompanying drawing wherein:

FIG. 1 is a fragmentary view of the feed station of a knitting machine embodying a throat plate construction of the present invention;

FIG. 2 is a plan view of the knitting machine feed station shown in FIG. l1 with the needle circle indicated thereon;

FIGS. 3 and 4 are sectional views taken on the lines 3-3 and 4 4 respectively of FIG. 2;

FIG. 5 is a detached perspective view of the throat plate with the portions thereof separated to more clearly illustrate the construction; and

FIG. 6 is a perspective View of the assembled throat plate detached from the knitting machine.

Referring now to the drawing, the main feed station of a multi-feed knitting machine is illustrated therein. The feed station comprises a yarn guide ring 10 having mounted therein a plurality of yarn feed fingers 11. The feed fingers 11are operated in a conventional manner to insert the yarn into and withdraw the yarn from a circle of needles 12 mounted for rotation in the machine. A latch ring liner 13 surrounds the circle of needles 12 and is formed with a gap 14 therein which registers with an opening 15 in the yarn guide ring in which the feed lingers 11 are mounted. Gap closing mechanism is provided at 16 and 17 to close the gap 14 when the feed fingers 11 are not being operated to insert or withdraw yarns. As shown in broken lines in FIG. 3, sinkers 18 cooperate with the needles 12 to form the knitted loops at the feed station.

A throat plate 21 bridges the opening 15 to underlie and support the feed linger 11a which is positioned for feeding yarn to the needle 12. The throat plate 21 comprises a non-ceramic support portion 22 and a ceramic tip portion 23. The support portion 22 is provided with a pair of apertures 24, 24 which are elongated as shown in FIGS. 2, 5, and 6 to receive fasteners 25. The elongated form of the apertures 24 permits minute adjustment of the throat plate 21 radially of the circle of needles 12 to properly position the ceramic tip portion 23 closely adjacent the circle. Locking means 26 is associated with each fastener to secure the throat plate in adjusted position. As shown in FIGS. 2, 4, 5, and 6, the outer surface 31 of the ceramic tip portion 23 is arcuate in form having a curvature corresponding to the curvature of the circle of needlesv 12, and positioned substantially concentric with said circle.

In accordance with the invention, the opposite surface.

32 of the tip portion 23 is optically flat and is adhesively secured to the confronting surface 34 of the support portion 22. The surface 34 is likewise machined to be optically flat so that the confronting optically ilat surfaces require only a thin lm of adhesive substance to insure a proper bond therebetween. Since the mating surfaces 32 and 34 are precision-finished, the manufacture and assembly of the parts avoids the imposition of stresses and `strains upon the ceramic tip portion 23 and thereby reduces to a minimum the likelihood of fracture of the brittle ceramic portion. Furthermore, since the mating surfaces are flat, they may be machined without the substantial difficulties that are present when irregular surfaces are machined. The lm of cement between the flat surfaces 32 and 34 forms a thin planar Vertical wall entirely separating the support portion from the tip portion, so that if the cement film should fracture or otherwise rupture, the tip portion may fall free from the support portion without hanging up thereon, thus avoiding damage to the knitting needles 12 and the associated structure.

The tip portion 23 is provided with a central recess 36 which is stepped as indicated at 41, and which receives the yarn from the feed fingers 11 when they are actuated to insert yarn into action, as shown in broken lines in FIG. 3. The support portion 22 is recessed as indicated at 37, the

recess having a width registering with the recess 36. TheV recess 37 receives the body portion of the feed ngers 11 and provides a vertical support for the same to insure accurate positioning thereof during the feeding of yarn to the needle circle 12. The yarn inserted by the linger 11a is therefore free to ride along the outer edge of the lower portion of the stepped recess 36 circumferentially of the tip portion, particularly in that portion of the knitting operation when the needle circle is reciprocated, as when forming the heel and toe pockets of the stocking.

The formation of the recess 37 in the support portion 22 provides a pair of upstanding pedestals 38 and 39 which bear against the yarn guide ring 10 when the throat plate 21 is mounted thereon. Preferably, the upper surfaces of the pedestals 38 and 39 are precision-ground so that when the fasteners 25 are tightened to secure the throat plate 21 in place, the precision grinding insures uniform pressure on both pedestals, eliminating the possibility of strain in the support portion which might distort the same and fracture the adhesive bond between the tip portion 23 and the support portion 22, or even fracture the ceramic tip portion 23 itself.

In accordance with another feature of the invention, in order to insure against fracture or chipping of the ceramic tip portion 23 by the feed fingers 11, the circumferential width of the recess 36 is slightly greater than the circumferential width of the recess 37 in the support portion 22. When the tip is assembled to the support portion, it is insured that the tip does not project into the recess between the pedestals 3S and 39 so that there is no possibility of the feed fingers striking the tip. By the same token, the bottom wall of the recess 36 is mounted flush with the bottom wall of the recess 37 so that the tip portion 23 does not project upwardly into the recess 37 between the pedestals 38 and 39. In the drawings, the difference in width of the recesses 36 and 37 has been exaggerated, in practice the difference being in the order of 0.0 inch to provide an overlap at each side of approximately 0.005 inch.

While a particular embodiment of the present invention has been herein illustrated and described, it is not intended to limit the invention to such disclosure, but changes and modifications may be made therein and thereto within the scope of the following claims.

We claim:

1. For the feed station of a circular knitting machine having a yarn guide ring with an opening therein and a latch ring liner mounted on said yarn guide ring, a plurality of feed fingers mounted for operation between an inoperative position and an operative position in said opening, and a circle of needles mounted for rotation within said guide ring and latch ring liner to receive yarn from the feed fingers in said opening, a throat plate construction comprising a non-ceramic support portion having a pair of pedestals adapted to be mounted on said yarn guide ring and defining therebetween a recess for receiving and supporting the feed fingers which are in position to introduce yarn to said needle circle, said support portion having a at surface thereon, a ceramic tip portion mounted on said support portion having a recess therein registering with said recess in the support portion, the outer surface of said tip portion being arcuate in form and projecting inwardly beyond said latch ring liner to deect the yarn from engagement with the latter, another surface of said tip portion being flat, and a cement operable to bond said flat surface of the tip portion to said flat surface of the support portion to constitute the only connection between said portions, the circumferential length of the recess in said ceramic tip portion being at least as great as the circumferential length of the recess between the pedestals in said support portion whereby said tip portion is prevented from engaging with said feed fingers as they are displaced between the inoperative and operative positions.

2. A throat plate construction according to claim l wherein the surfaces of said pedestals which engage against said yarn guide rings are precision-ground to prevent strain on said support portion and thereby prevent distortion thereof which would fracture the bond provided by said cement or fracture the ceramic tip portion.

3. For the feed station of a circular knitting machine having a yarn guide ring with an opening therein, a plurality of feed fingers mounted in said opening, and a circle of needles mounted for rotation within said guide ring to receive yarn from the feed fingers in said opening; a throat plate construction comprising a non-ceramic support portion having a pair of pedestals adapted to be mounted on said yarn guide ring and defining therebetween a recess for receiving and supporting the feed fingers which are in position to introduce yarn to said needle circle, said support portion having an optically at surface thereon, confronting the needle circle, a ceramic tip portion mounted on said support portion having a recess therein registering with said recess in the support portion, the outer surface of said tip portion being arcuate in form with a curvature corresponding substantially to the curvature of said circle of needles, the opposite surface of said tip portion being optically flat, and a cement disposed between said portions to bond said optically flat surface of said tip portion to said optically flat surface of the support portion to constitute the only connection between said portions, the circumferential length of the recess in said ceramic tip portion being greater than the circumferential length of the recess between the pedestals in said support portion whereby said tip portion does not project into the recess of said support portion and is thereby prevented from engaging with said feed fingers as they are displaced between their operative and inoperative positions.

4. For the feed station of a circular knitting machine having a yarn guide ring with an opening therein, a plurality of feed fingers mounted for operation between an inoperative position and an operative position in said opening, and a circle of needles mounted for rotation within said guide ring to receive yarn from the feed fingers in said opening, a throat plate construction comprising a non-ceramic support portion having a pair of pedestals adapted to be mounted on said yarn guide ring and defining therebetween a recess for receiving and supporting the feed fingers which are in position to introduce yarn to said needle circle, said support portion having a flat surface thereon, a ceramic tip portion mounted on said support portion having a recess therein registering with said recess in the support portion, the outer surface of said tip portion being arcuate in form, another surface of said tip portion being hat, and a film of cement intermediate the flat surfaces of the tip portion and support portion operable to bond said portions together and to serve as a thin planar vertical wall entirely separating said portions and to constitute the only connection therebetween whereby upon rupture of said film, said tip portion may fall free from said support portion, the circumferential length of the recess in said ceramic tip portion being at least as great as the circumferential length of the recess between the pedestals in said support portion whereby said tip portion is prevented from engaging with said feed fingers as they are displaced between the inoperative and operative positions.

References Cited in the le of this patent UNITED STATES PATENTS 1,388,595 Olbon Aug. 23, 1921 2,896,434 McKinley et al Iuly 28, 1959 2,946,209 Haas July 26, 1960 3,004,733 Spivey Oct. 17, 1961 

